This invention relates to devices for limiting the travel of an air door in a disk cartridge.
Disk cartridges of the type fully described in American National Standard -- X3.52 -- 1976, available from the American National Standards Institute, 1430 Broadway, New York, New York 10018 (the content whereof is incorporated herein by reference), have an air inlet port through which filtered air may flow into the disk cartridge from a disk drive unit with which the cartridge is engaged. Normally associated with the air inlet port is an air door assembly. This air door assembly includes an air door adapted to cover the air inlet port, and means normally biasing the air door to a closed position over the air inlet port from which the air door can be moved to an open position against the influence of the biasing means when a member on the drive unit engages the air door.
As may be seen in FIGS. 1, 2 and 3 of the drawing, one prior art air door assembly commonly used on a cartridge 11 of the aforementioned type comprises a spring steel plate 10 having a generally U-shaped slot 12 closely spaced from the periphery of the plate on three sides to define a large portion of the plate 10 providing the air door 14 which is shaped to extend across the air inlet port 16 (FIG. 1) in a circular housing 18 for the disk cartridge 11 on the inner surface 17 of the housing 18 (FIG. 2). The slot 12 also defines a generally U-shaped portion of the plate 10 which provides a biasing strip 21 extending around three sides of the air door 14. The biasing strip includes a central length or portion 22 which is fixedly attached to the housing 18 as by two rivets 23, and side lengths 24 which extend generally radially outwardly of the housing 18 from the central portion 22 and attach the central portion 22 to the air door 14. The side lengths 24, being resiliently flexible, will bend sinuously into two arcuate portions to afford movement of the air door 14 away from the inner surface 17 of the housing 18 in an attitude which may or may not be generally parallel thereto.
This prior art air door assembly also includes means for limiting movement of the air door 14 away from the housing 18 including two metal hook-like members 26 projecting from a common base 27 attached over the central portion 22 of the biasing strip 21 by the rivets 23. The projecting hook-like members 26 engage the air door 14 adjacent its inner edge when that edge reaches a full open position, and thereby restrict engagement of the air door 14 with a disk 28 in the cartridge 11 which might cause scratching or marring of the magnetizable coating on the disk 28. Such hook-like members 26, however, present potential problems in that it is possible during handling of the disk cartridge 11 removed from a disk drive to displace the disk 28 which is loosely retained within the cartridge 11 so that the disk 28 impinges against the hook-like members 26 and the magnetic coating on the disk 28 is damaged, thereby making the disk 28 unsuitable for recording data, and possibly losing prerecorded information.